Neoadjuvant botensilimab/balstilimab is active in resectable colon cancer, despite MMR status

During the meeting, the FDA and Agenus reached an agreement on the recommended dose for a phase III study of 75 mg of botensilimab once every 6 weeks for up to 4 doses plus 240 mg of balstilimab once every 2 weeks for up to 2 years. Notably, the FDA also recommended the inclusion of a botensilimab monotherapy arm in the phase III study at the discretion of Agenus.

Interim topline data from the phase II study showed that patients treated with the 75-mg dose of botensilimab plus balstilimab (n = 62) experienced an ORR of 19.4% (95% CI, 10.4%-31.4%). In this arm, the 6-month overall survival (OS) rate was 90%. In patients given the 150-mg dose of botensilimab plus balstilimab (n = 61), the ORR was 8.2% (95% CI, 2.7%-18.1%). Notably, botensilimab monotherapy given at 75 mg once every 6 weeks (n = 38) and at 150 mg once every 6 weeks (n = 40) elicited ORRs of 0% (95% CI, 0%-9.3%) and 7.5% (95% CI, 1.6%-20.4%), respectively. In the standard-of-care (SOC) arm (n = 33), the ORR was 0% (95% CI, 0%-10.6%).

“Based on the high level of enthusiasm from significant numbers of global clinical experts and the promising clinical activity we have seen in the phase 1 and II studies, our commitment to seek all possible pathways to make botensilimab/balstilimab available to patients is unwavering,” Steven O’Day, MD, chief medical officer of Agenus, stated in a news release. “This includes exploring opportunities to partner in the United States to accomplish a successful phase III trial.